Transmission Investments in a Multilateral Context

More and more transmission planning has to cope with a multilateral context due to increased electricity exchanges between zones. Whereas investments are decided upon and approved at the zonal level, policy goals can be formulated at a higher supranational level. The zonal level, however, can have its own objectives or way to reach the policy goals. This is possibly conflicting with the supranational or other zones´ viewpoints. In this paper, different transmission investment planners are compared. Conflicting outcomes are observed. As a possible compromise, a Pareto-planner is proposed. He maximizes overall welfare while guaranteeing that all zones can at least keep their initial level of welfare. These constraints ensure that the multilateral context is explicitly taken into account. All planners are modeled as bilevel optimization problems and solved using mixed-integer quadratic programming and genetic algorithm. The models are applied on a three-node and 14-node example.